Hello fellow CBR Riders! So I have been tuning up a 92 cbr600f2 I got for a steal ($250). Previous owner could not get it to turn over; well after a quick fuse change its started right up. I have done a basic tune up (plugs, wires, oil, filter , ect). The issue I seem to be running into is I can not get the idle to settle. It will start low then once you rev it up it stays around 3k? you can crank back on the throttle to get It back down but if you don't hold it then it will quickly rise again. I have checked all my cables (chock, throttle, ect) and everything seems in working order. I did have to do a minor rebuild on the carbs because for some reason the previous owner bent all the valves on the inside. Should I try replacing the carbs all together or... Any suggestions would be much appreciated. Thank you in advance and stay safe out there!

 

Could be a sync issue.

 

You have an air leak some where, maybe the emulsion tubes are worn out, good chance both. I had this issue with my F3 and it was the emulsion tubes and main needle. On Yami's, you can replace the emulsion tubes. However, Honda didn't allow this.
Lets start with the air leaks first. What condition are the carb insulators in? If they are hard as rock, cracked, or both, then they need to be replaced. Look at the air passages with rubber hoses and garments between the carbs, are they cracked and dried out. There is also a good chance your carbs haven't been serviced in a decade or so and things just need to be replaced.